1. Field of the Invention
The present invention concerns a variable speed transmission mechanism, adapted for use in bicycles for example, wherein the working diameter of the bicycle sprocket wheel or driving member of the transmission is increased or decreased responsive to variations in pedal pressure by the feet of the bicycle rider.
2. Description of the Prior Art
Apparatus suitable for varying the effective diameter of a bicycle sprocket wheel operable as the driver member of a variable speed transmission has been disclosed in the patent to Hunt U.S. Pat. No. 3,798,989. The settings of a sprocket diameter therein illustrated are controlled by a manually operable so-called "interposer", which forces a plurality of coacting segments radially outwardly, thereby increasing the sprocket wheel diameter. The interposer also releases such segments to effect a retraction of the segments thereby decreasing the diameter of the sprocket wheel.
While the Hunt transmission mechanism above summarized does not require a plurality of sprockets or cooperating derailleur mechanisms (such as other conventional bicycle transmissions require (it does entail a hand operated transmission shift and is limited to achieve a relatively small number of speed ratios or speed capabilities.